Drifting valve



Jan. 13, 1925. 1,523,076

P. E. MCMILLIAN DRIFTING VALVE Filed Jan. 2v.` 1922 .Ml-MIMI@ ma wmf ellifoz new.

Patented Jan. 13, '1925.

PRESTON E. IVICMLLIN, O'F FLORENCE, SOUTH CAROLINA, ASSIGNOR GF ONE-HALF TO i GEORGE W. LAUGHLIN, OF FLORENCE, SOUTH CAROLINA.

DRIETIN G VALVE.

application inea January 27, 1922.

T0 all 107mm t muy concern.'

Be it .known that I, PRESTON E. Meh/11n LniN, citizen of the United States.` of America, residing at Florence, in the county A of Florence and State of South Carolina,

have4v invented certain new and useful Improvements in Drifting Valves, of which the following is a specification.

My invention relates to improvements in drifting valves for locomotives and has for its object the construction of a valve which may be inexpensively manufactured, which is composed of few parts, which acts autor matically efiiciently, and which may be readily installed on a locomotive.

A further object of my invention- 1s the construction of a valve which will convey saturated steam into the cylinders when the throttle isV shut olf in order toprevent injury to the cylinders resulting from the use of superheated steam.

A further object is to construct a valve which will do away with the vacuum created in the steam chest or cylinders when the throttle is shut ofi".

A still further object of my invention is to construct a valve whichl will automatically shut oif the saturated steam from the cylinders when the engine has'been stopped after it has Vbeen drifting and the drifting' valve has been in operation.

YllVith th-ese and further objects in view, one embodiment of my invention is shown in the accompanying drawing, in which:

Figure l is a side elevation showing diagrammatical'ly the position and connections of my improved valve around. the upper part of the boiler of a steam locomotive, the boiler not being shown; and

Figure 2 is a vertical' section through the valve.

My invention is indicated generally by the numeral 1. This valve may be placed around the upper part of the boiler of' a steam" locomotive, not shown, justback of the, smoke-stack. A pipe 2 conveys steam from the turret or steam dome to an upper chamber in the valve. Connecting the steam chests 3, which are connected 'with the cylinders l1, is a tube 5, which also connects with the bottom of thevalve. The pipes 6 connect the upper chamber with which the pipe 2 connects with the connecting tube 5 when the throttle is closed and the valve operates, as will be more fully herein set forth.

positionfits in a `upper piston head 21 is a port 24 to permit Serial No. 532,247.

flhe pipes G may be connected tothe connecting tube 5 by means of joints 7, or in any other suitable manner. l

The valve casing consists of a lower part 8 and an upper part 9 connected in any suitable manner as by screw threads. The casing is attached to the connecting` tube in anv suitable manner, as by means of screw threads 10. Hthin the casing are an upper chamber 11, a middle chamber 12, and a lower chamber 13, in which a valve piston 1-1 reciprocates. This valve piston is supported in closed position by a spring 15, the lower end of which is seated on a bar 16 across the lower chamber 13. end of the spring fits in anopening 17 in the bottom of the piston. This spring is madeV suihciently strong to support the valve piston in closed position when there is no downward pressure on the valve piston head to overcome the pressure under the lower piston head. A lower pistonhead 18 separates a middle chamber 12 and a lower chamber 13 and has. therethrough a port 19 which permits the exchange of steam between the chambers 12 and 13. A piston stem 2O which reciprocates in the upper chamber 11 `has at the upper end thereof an upper head 21. y This piston stem has near the middle part thereof a valve piston head 22,`the head 22 when thepiston is in closed valve seat 23. Above the the escape of any steam which passes around the upper piston head. All piston heads have suitable packing rings 18a, 21a, and 22u. lt will be noted that the area of the upper piston head 2l and the area of the piston valvehead 22 exposed to the steam from the steam dome are the same when the valve is closed.

rlfhe operation of my valve may be described as follows: Then the throttle is `open and steam is in the cylinders and steam chests, the piston will be in the position indicated in full lines, and the superheated steam will fill the chambers 12 and 13. As soon as the throttle is shut off the steam in chamber 13 will be exhausted very rapidly, thereby leaving the steam in chamber 12 to force the piston down into the position shown in dotted lines in Figure 2, "hich permits the saturated steam brought into chamber 11 by pipe 2 to flow through pipe 6 and connecting tube 5 into the steam chests The upper b lll This flow of steam will conthe throttle is closed and the engine is drifting. After the steam in chamber l2 has forced the valve down, then the steam brought in through pipe 2 will hold it down, due to the area of the piston head 22 being larger than the area of the piston head 21.

The valve will continue to operate to convey saturated steam into the cylinders until the throttle is again opened or until the engine is stopped. Then the throttle is opened the pressure of the steam on the bottom of the lower piston head 1S will force the valve piston head to closed position and close the valve. Then the engine is stopped the valve will remain in open position until the steam pressure in the cylinders and steam chest is su'liiciently strong to force the piston upward to closed position and to cause the valve piston head 22 to seat and close the valve. The upward movement of the piston will result from the accumulated steam because the area of the bottom of piston head 18 exposed to steam pressure in chamber 13 is much larger than the area of the top of piston head 18 in chamber 1Q.

Having described my invention, claim, and desire to secure by Letters ent, .is:- Y

l. A drifting valve for locomotives, comprising a casing having upper, middle and lower chambers therein, a valve piston in said chambers, resilient supporting means for said piston, a connection between said lower chamber and the steam chest of a locomotive, a connection between said lower chamber and said middle chamber, a connection between said upper chamber and a source of saturated steam ina locomotive when said valve piston is in closed position, and another connection between said upper chamber and the steam chest of a locomotive when said valve piston is in open position; Y

2. A drifting valve for a locomotive comprising a casing having upper, middle, and lower chambers therein, a connection between said upper chamber and a source of saturated steam, also a connection between said upper chamber and the steam chest of a locomotive, a valve piston having an upper head, a valve head and a lowerhead reciprocating in said chambers and controlling said connections, spring means to hold said valve piston in closed position and means to cause said valve piston to move from closed to open position whereby the connection'between the upper chamber and thesteam chest of a locomotive is opened, said means comprising the lower piston head located between the lower chamber and the middle chamber and said lower piston head having a steam port therein whereby said chambers are connected.

and cylinders. tmue as long as what I Pat- 3. A drifting valve for locomotives, oomprising a casing, said casing having upper, middle and lower chambers therein, a valve piston adapted to reciprocate in said cham-- bers, a connection between said upper chamber and a source of saturated steam, a connection between said lower chamber and the cylinders of a locomotive, a restricted connection between said lower chamber and said middle chamber, means to cause said valve piston to move to open position, anda connection between said upper chamber and the cylinders of a locomotive when said valve piston is in open position. Y Y

4. In combination with a locomotive having a steam supply, a steam chest, and steam cylinder, of a drifting valve comprising a casing having an upper chamber therein, a connection between said upper chamber and a steam supply, said casing having a lower chamber therein, a valve piston adapted to reciprocate in said chambers, said valve piston having an upper head,a lower head, and a valve head, said upper' head and valve head closing the outlets of said upper chamber, the area of the said heads closing the upper chamber and exposed tosteam ,pressure being equal when said valve piston is in closed position, the area of the said heads being unequal when said valve piston is in open position, a connection between said upper chamberl and said steamchest when said valve piston is in open position and a connection between said lower chamberand said steam chest.

5. A device of the kind described, comprising a casing having upper, middle and lower chambers therein, a Vconnection between one of said chambers and. a steam supply, a connection between anotherv of said chambers and the cylinders of a locomotive, a valve piston, means to hold said piston in'closed position when the throttle of the locomotive is open, and

means to move said valve piston to open position when said throttle is closed, whereby steam passes from a steam source through said upper chamber to the cylinders of a locomotive, said means comprising a lower piston head separating the middle chamber from the lower chamber, said lower chamber being connected with the steam cylinders, and said middle chamber being connected with said lower chamber by aconnection so small that when the steam is exhausted from the cylinders by closing the throttle, the steam pressure inthe middle move the piston to open position.

6. In a drifting valve for locomotives, a casing, a valve piston in said casing adapted to reciprocate therein, said valve piston being held in closed position by resilient means, andesaid valve piston having upper and lower heads, and a valve head said casing having an upper chamber, a connection chamber will between said upper chamber and a source ot saturated steam, means to move said valve piston to open position by pressure on the upper side of the lower piston head, whereby a connection between a source of satura-ted steam and the cylinders of a locomotive is established, and means to retain the valve piston in open position while the throttle is closed and the locomotive is running, said means comprising the valve piston head having a greater area exposed to steam from the steam source when the valve piston is in open position than the area of the upper piston head exposed to steam when the valve piston is in open position.

7. A device of the kind described, comprising a easing` having upper, middle and lower chambers therein, a connection between the upper chamber and a steam supply, a connection between the lower chamber and the cylinders of a locomotive, a valve piston, means to hold said valve piston in closed position when the throttle of the locomotive in open, means to move said valve piston to open position when said throttle is closed, whereby steam passes from a. steam source through said upper chamber to the cylinders of a locomotive, and means to move said valve piston to closed position when the locomotive is stopped, said means comprising a lower piston head one side of which is connected with a steam supply and means connecting the two sides Vof the piston head,

one side of the piston head having a greater area than the other side thereof.

In testimony whereof I ailiX my signature.

PRESTON E. MCMILLIAN. 

